Plasma processing apparatus

ABSTRACT

Temperature uniformity in a mounting surface of a mounting table is improved. A plasma processing apparatus includes a mounting table having thereon a mounting surface on which a work-piece serving as a plasma processing target is mounted; a coolant path formed within the mounting table along the mounting surface of the mounting table; an inlet path connected to the coolant path from a backside of the mounting surface of the mounting table and configured to introduce a coolant into the coolant path; and a thermal resistor provided in a region, facing a connection portion between the inlet path and the coolant path, of an inner wall of the coolant path.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2018-063520 filed on Mar. 29, 2018, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The embodiments described herein pertain generally to a plasma processing apparatus.

BACKGROUND

Conventionally, there has been known a plasma processing apparatus configured to perform plasma processing, such as etching, on a work-piece, such as a semiconductor wafer, with plasma. In the plasma processing apparatus, a coolant path is provided within a mounting table, on which the work-piece is placed, along a mounting surface of the mounting table to perform a temperature control on the work-piece. An inlet path is connected to the coolant path from a backside of the mounting surface of the mounting table, so that a coolant is introduced into the coolant path from the inlet path.

Patent Document 1: Japanese Patent Laid-open Publication No. 2006-261541

Patent Document 2: Japanese Patent Laid-open Publication No. 2011-151055

Patent Document 3: Japanese Patent Laid-open Publication No. 2014-011382

SUMMARY

The embodiments disclosed herein provide a technology capable of improving the temperature uniformity in a mounting surface of a mounting table.

A plasma processing apparatus includes a mounting table having thereon a mounting surface on which a work-piece serving as a plasma processing target is mounted; a coolant path formed within the mounting table along the mounting surface of the mounting table; an inlet path connected to the coolant path from a backside of the mounting surface of the mounting table and configured to introduce a coolant into the coolant path; and a thermal resistor provided in a region, facing a connection portion between the inlet path and the coolant path, of an inner wall of the coolant path.

According to the exemplary embodiments of the plasma processing apparatus disclosed herein, it is possible to obtain an effect of improving the temperature uniformity in the mounting surface of the mounting table.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description that follows, embodiments are described as illustrations only since various changes and modifications will become apparent to those skilled in the art from the following detailed description. The use of the same reference numbers in different figures indicates similar or identical items.

FIG. 1 is a schematic cross sectional view illustrating a configuration of a plasma processing apparatus according to an exemplary embodiment;

FIG. 2 is a schematic cross sectional view illustrating a configuration of main components of a mounting table according to a first exemplary embodiment;

FIG. 3 is a plan view of the mounting table when viewed from the top;

FIG. 4 is a schematic cross sectional view illustrating an example of a thermal resistor according to the first exemplary embodiment;

FIG. 5 is a diagram schematically showing a state of a coolant which flows through a coolant path;

FIG. 6 is a schematic cross sectional view showing a first modification example of the thermal resistor according to the first exemplary embodiment;

FIG. 7 is a schematic cross sectional view showing a second modification example of the thermal resistor according to the first exemplary embodiment;

FIG. 8 is a schematic cross sectional view showing a modification example of connection between an inlet path and the coolant path according to the first exemplary embodiment;

FIG. 9 is a schematic cross sectional view illustrating a configuration of main components of a mounting table according to a second exemplary embodiment;

FIG. 10 is a schematic cross sectional view illustrating an example of a thermal resistor according to the second exemplary embodiment;

FIG. 11 is a schematic cross sectional view showing a first modification example of the thermal resistor according to the second exemplary embodiment;

FIG. 12 is a schematic cross sectional view showing a second modification example of the thermal resistor according to the second exemplary embodiment; and

FIG. 13 is a schematic cross sectional view showing a third modification example of the thermal resistor according to the second exemplary embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part of the description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Furthermore, unless otherwise noted, the description of each successive drawing may reference features from one or more of the previous drawings to provide clearer context and a more substantive explanation of the current exemplary embodiment. Still, the exemplary embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings, may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

Hereinafter, exemplary embodiments of a plasma processing apparatus disclosed herein will be described in detail with reference to the accompanying drawings. Further, the present disclosure is not limited to the exemplary embodiments.

Conventionally, there has been known a plasma processing apparatus configured to perform plasma processing, such as etching, on a work-piece, such as a semiconductor wafer, with plasma. In the plasma processing apparatus, a coolant path is provided within a mounting table, on which the work-piece is placed, along a mounting surface of the mounting table to perform a temperature control on the work-piece. An inlet path is connected to the coolant path from a backside of the mounting surface of the mounting table, so that a coolant is introduced into the coolant path from the inlet path.

However, if the inlet path is connected to the coolant path from the backside of the mounting surface of the mounting table, a flow velocity of the coolant is locally increased in a region, facing a connection portion between the inlet path and the coolant path, of an inner wall of the coolant path. Therefore, a thermal boundary layer serving as a thermal resistance may not be formed or may become thinner. For this reason, in the region, facing the connection portion between the inlet path and the coolant path, of the inner wall of the coolant path, heat transfer from the mounting surface of the mounting table to the coolant is locally promoted, so that the temperature uniformity in the mounting surface of the mounting table is deteriorated.

First Exemplary Embodiment Configuration of Plasma Processing Apparatus

FIG. 1 is a schematic cross sectional view illustrating a configuration of a plasma processing apparatus according to the present exemplary embodiment. A plasma processing apparatus 100 includes a processing chamber 1 configured to be airtightly sealed and electrically grounded. The processing chamber 1 has a cylindrical shape and is made of, e.g., aluminum. The processing chamber 1 partitions a processing space where plasma is generated. Within the processing chamber 1, there is provided a mounting table 2 configured to horizontally mount thereon a semiconductor wafer (hereinafter, simply referred to as “wafer”) W serving as a work-piece. The mounting table 2 includes a base 2 a and an electrostatic chuck 6 (ESC). The base 2 a is made of a conductive metal such as aluminum or the like and serves as a lower electrode. The electrostatic chuck 6 is configured to electrostatically attract the wafer W. The mounting table 2 is supported by a support 4. The support 4 is supported by a supporting member 3 made of, e.g., quartz. Further, a focus ring 5 made of, e.g., single crystalline silicon is provided on an upper periphery portion of the mounting table 2. Furthermore, within the processing chamber 1, a cylindrical inner wall member 3 a made of, e.g., quartz is provided to surround the mounting table 2 and the support 4.

The base 2 a is connected to a first RF power supply 10 a via a first matching unit 11 a, and also connected to a second RF power supply 10 b via a second matching unit 11 b. The first RF power supply 10 a is provided for plasma generation and configured to supply a high frequency power having a predetermined frequency to the base 2 a of the mounting table 2. Further, the second RF power supply 10 b is provided for ion attraction (for bias) and configured to supply a high frequency power having a predetermined frequency lower than that of the first RF power supply 10 a to the base 2 a of the mounting table 2. As such, a voltage can be applied to the mounting table 2. Meanwhile, above the mounting table 2, a shower head 16 serving as an upper electrode is provided to face the mounting table 2 in parallel to each other. The shower head 16 and the mounting table 2 are configured to serve as a pair of electrodes (upper electrode and lower electrode).

The electrostatic chuck 6 has a flat disc-shaped upper surface, and the upper surface serves as a mounting surface 6 e on which the wafer W is mounted. The electrostatic chuck 6 includes an electrode 6 a embedded within insulators 6 b, and the electrode 6 a is connected to a DC power supply 12. Further, a DC voltage is applied from the DC power supply 12 to the electrode 6 a, so that the wafer W is attracted by a Coulomb force.

Within the base 2 a, a coolant path 2 d is formed. One end of the coolant path 2 d is connected to an inlet path 2 b and the other end thereof is connected to an outlet path 2 c. The inlet path 2 b and the outlet path 2 c are connected to a non-illustrated chiller unit via a coolant inlet line 2 e and a coolant outlet line 2 f, respectively. The coolant path 2 d is located under the wafer W and configured to absorb heat of the wafer W. The plasma processing apparatus 100 is configured to control the mounting table 2 to have a predetermined temperature by circulating a coolant, e.g., cooling water or an organic solvent such as Galden, supplied from the chiller unit through the coolant path 2 d. The structures of the coolant path 2 d, the inlet path 2 b, and the outlet path 2 c will be described later.

Further, the plasma processing apparatus 100 may be configured to supply a cold heat transfer gas to a backside of the wafer W to independently control the temperature. For example, a gas supply line, through which the cold heat transfer gas (backside gas) such as a helium gas or the like is supplied to the rear surface of the wafer W, may be provided to pass through the mounting table 2. The gas supply line is connected to a non-illustrated gas supply source. With this configuration, the wafer W attracted to and held on the upper surface of the mounting table 2 by the electrostatic chuck 6 is controlled to have a predetermined temperature.

The shower head 16 is provided at a ceiling wall of the processing chamber 1. The shower head 16 includes a main body 16 a and an upper ceiling plate 16 b serving as an electrode plate, and is supported at an upper portion of the processing chamber 1 with an insulating member 95 therebetween. The main body 16 a is made of a conductive material, e.g., aluminum having an anodically oxidized surface, and configured to support the upper ceiling plate 16 b on a lower portion thereof in a detachable manner.

A gas diffusion space 16 c is formed within the main body 16 a. Further, multiple gas through holes 16 d are formed in a bottom portion of the main body 16 a to be extended from the gas diffusion space 16 c. Furthermore, gas discharge holes 16 e passing through the upper ceiling plate 16 b in a thickness direction thereof are formed to communicate with the gas through holes 16 d, respectively. With this configuration, a processing gas supplied into the gas diffusion space 16 c is dispersed in a shower shape and supplied into the processing chamber 1 through the gas through holes 16 d and the gas discharge holes 16 e.

A gas inlet opening 16 g through which a processing gas is introduced into the gas diffusion space 16 c is formed in the main body 16 a. The gas inlet opening 16 g is connected to one end of a gas supply line 15 a. A processing gas supply source (gas supplying unit) 15 configured to supply a processing gas is connected to the other end of the gas supply line 15 a. A mass flow controller (MFC) 15 b and an opening/closing valve V2 are sequentially provided from an upstream side at the gas supply line 15 a. A processing gas for plasma etching is supplied into the gas diffusion space 16 c through the gas supply line 15 a from the processing gas supply source 15. The processing gas is dispersed in a shower shape and supplied into the processing chamber 1 through the gas through holes 16 d and the gas discharge holes 16 e from the gas diffusion space 16 c.

A variable DC power supply 72 is electrically connected to the shower head 16 serving as the upper electrode via a low pass filter (LPF) 71. The variable DC power supply 72 is configured to turn on/off power supply by using an on/off switch 73. A current/voltage of the variable DC power supply 72 and an on/off operation of the on/off switch 73 are controlled by a control unit 90 to be described later. Further, as will be described later, when plasma is generated in the processing space by applying the high frequency powers from the first RF power supply 10 a and the second RF power supply 10 b to the mounting table 2, the on/off switch 73 is turned on by the control unit 90, if necessary, so that a predetermined DC voltage is applied to the shower head 16 serving as the upper electrode.

A cylindrical ground conductor 1 a is provided to be upwardly extended from the side wall of the processing chamber 1 to a position higher than a height position of the shower head 16. The cylindrical ground conductor 1 a has a ceiling wall at an upper portion thereof.

An exhaust opening 81 is formed at a bottom portion of the processing chamber 1. A first exhaust device 83 is connected to the exhaust opening 81 via an exhaust pipe 82. The first exhaust device 83 has a vacuum pump, and the inside of the processing chamber 1 can be decompressed to a predetermined vacuum level by operating the vacuum pump. Meanwhile, a carry-in/carry-out opening 84 for the wafer W is formed at the side wall of the processing chamber 1, and a gate valve 85 configured to open or close the carry-in/carry-out opening 84 is provided at the carry-in/carry-out opening 84.

On an inner sidewall of the processing chamber 1, a deposition shield 86 is provided along an inner wall surface. The deposition shield 86 is configured to suppress an etching by-product (deposit) from being attached on the processing chamber 1. At the deposition shield 86, a conductive member (GND block) 89, which is connected such that its potential with respect to the ground may be controlled, is provided at substantially the same height position as that of the wafer W, so that an abnormal electric discharge is suppressed. Further, at a lower end portion of the deposition shield 86, there is provided a deposition shield 87 extended along the inner wall member 3 a. The deposition shields 86 and 87 are detachably attached.

An overall operation of the plasma processing apparatus 100 configured as described above is controlled by the control unit 90. The control unit 90 includes a process controller 91 that includes a CPU and controls each component of the plasma processing apparatus 100, a user interface 92, and a storage unit 93.

The user interface 92 includes a keyboard through which a process manager inputs a command to manage the plasma processing apparatus 100; and a display that visibly displays an operation status of the plasma processing apparatus 100.

The storage unit 93 stores a recipe of a control program (software) or processing condition data for implementing various processes executed in the plasma processing apparatus 100 to be performed under the control of the process controller 91. Then, if necessary, a desired process is performed in the plasma processing apparatus 100 under the control of the process controller 91 by retrieving a certain recipe from the storage unit 93 in response to an instruction or the like from the user interface 92 and executing the corresponding recipe in the process controller 91. Further, the recipe of the control program, the processing condition data, or the like may be stored in a computer-readable storage medium (for example, a hard disc, a CD, a flexible disc, a semiconductor memory, or the like), or may also be frequently transmitted on-line from another apparatus via, e.g., a dedicated line.

Configuration of Mounting Table

Hereafter, a configuration of main components of the mounting table 2 will be described with reference to FIG. 2. FIG. 2 is a schematic cross sectional view illustrating a configuration of main components of the mounting table 2 according to a first exemplary embodiment.

The mounting table 2 includes the base 2 a and the electrostatic chuck 6. The electrostatic chuck 6 has a circular plate shape and is fixed to the base 2 a to be coaxially arranged with the base 2 a. The upper surface of the electrostatic chuck 6 serves as the mounting surface 6 e on which the wafer W is mounted.

Within the base 2 a, the coolant path 2 d is provided along the mounting surface 6 e. The plasma processing apparatus 100 is configured to control the temperature of the mounting table 2 by allowing the coolant to flow through the coolant path 2 d.

FIG. 3 is a plan view of the mounting table 2 when viewed from the top. In FIG. 3, the mounting surface 6 e of the mounting table 2 is illustrated as having a circular plate shape. The coolant path 2 d is formed to have, e.g., a vortex shape in a region, corresponding to the mounting surface 6 e, within the base 2 a, as shown in FIG. 3. Thus, the plasma processing apparatus 100 can control the temperature of the wafer W on the entire mounting surface 6 e of the mounting table 2.

Referring to FIG. 2 again, the inlet path 2 b and the outlet path 2 c are connected to the coolant path 2 d from the backside of the mounting surface 6 e of the mounting table 2. The inlet path 2 b introduces the coolant into the coolant path 2 d, and the outlet path 2 c drains the coolant flowing through the coolant path 2 d. For example, the inlet path 2 b is extended from the backside of the mounting surface 6 e of the mounting table 2 such that an extension direction of the inlet path 2 b is orthogonal to a flow direction of the coolant flowing through the coolant path 2 d, and then, is connected to the coolant path 2 d. Further, for example, the outlet path 2 c is extended from the backside of the mounting surface 6 e of the mounting table 2 such that an extension direction of the outlet path 2 c is orthogonal to the flow direction of the coolant flowing through the coolant path 2 d, and then, connected to the coolant path 2 d.

The coolant path 2 d is provided with a thermal resistor 110 in a region, facing a connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d.

FIG. 4 is a schematic cross sectional view illustrating an example of the thermal resistor 110 according to the first exemplary embodiment. FIG. 4 corresponds to a cross sectional view taken along a line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. The thermal resistor 110 is made of the same material as the base 2 a of the mounting table 2. For example, the thermal resistor 110 is made of a conductive metal such as aluminum, titanium, stainless steel, or the like. The thermal resistor 110 is provided as a single body with the base 2 a of the mounting table 2 to be protruded toward the connection portion 2 g from the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. That is, when viewed from a direction orthogonal to the mounting surface 6 e, the thermal resistor 110 is provided at a position overlapping with the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, and a thickness of a portion, located above the connection portion 2 g, of the base 2 a of the mounting table 2 is greater than the thickness of the other portion. In the present exemplary embodiment, the thermal resistor 110 has a shape in which a thickness thereof is uniform in the flow direction of the coolant flowing through the coolant path 2 d (as indicated by an arrow in FIG. 4).

However, in the plasma processing apparatus 100, if the inlet path 2 b is connected to the coolant path 2 d from the backside of the mounting surface 6 e of the mounting table 2, the temperature uniformity in the mounting surface 6 e of the mounting table 2 may be deteriorated.

FIG. 5 is a diagram schematically showing a state of a coolant which flows through the coolant path 2 d. As shown in FIG. 5, the coolant path 2 d is provided within the base 2 a along the mounting surface 6 e of the mounting table 2. Further, the inlet path 2 b is connected to the coolant path 2 d from the backside of the mounting surface 6 e of the mounting table 2. In the plasma processing apparatus 100 in which the inlet path 2 b is connected to the coolant path 2 d from the backside of the mounting surface 6 e of the mounting table 2, the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d. When the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d, a flow velocity of the coolant is locally increased in the region, facing the connection portion 2 g between the coolant path 2 d and the inlet path 2 b, of the inner wall of the coolant path 2 d. Therefore, a thermal boundary layer serving as a thermal resistance may not be formed or may become thinner. Meanwhile, in the other region except the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d, the thermal boundary layer serving as the thermal resistance is formed. In FIG. 5, the thermal boundary layer formed in the other region except the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d is illustrated as a layer indicated by a broken line. A thermal resistance R1 between the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d and the mounting surface 6 e is decreased by a thermal resistance of the thermal boundary layer as compared with a thermal resistance R2 between the other region of the coolant path 2 d and the mounting surface 6 e. For this reason, in the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d, heat transfer from the mounting surface 6 e to the coolant is locally promoted, so that the temperature uniformity in the mounting surface 6 e of the mounting table 2 is deteriorated.

Meanwhile, in the plasma processing apparatus 100, the thermal resistor 110 is provided in the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d, as shown in FIG. 2 and FIG. 4. That is, since the thermal resistor 110 is provided in the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d, the a thermal resistance between the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d and the mounting surface 6 e is increased. Thus, the thermal resistance R1 between the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d and the mounting surface 6 e can be made close to the thermal resistance R2 between the other region of the coolant path 2 d and the mounting surface 6 e. That is, the thermal resistor 110 can reduce a deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e. Thus, it is possible to improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Further, the thermal resistor 110 may have an inclined shape in which a thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d. FIG. 6 is a schematic cross sectional view showing a first modification example of the thermal resistor 110 according to the first exemplary embodiment. FIG. 6 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. In FIG. 6, the flow direction of the coolant flowing through the coolant path 2 d is indicated by an arrow. The thermal resistor 110 illustrated in FIG. 6 has an inclined surface, so that a thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d (as indicated by the arrow in FIG. 6). Thus, even if the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d, the increase in the flow velocity of the coolant in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d is suppressed. Accordingly, the thermal boundary layer serving as the thermal resistance is more likely to be formed in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. For this reason, the thermal resistor 110 can further reduce the deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e. Thus, it is possible to further improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Moreover, the thermal resistor 110 may have a curved shape in which a thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d. FIG. 7 is a schematic cross sectional view showing a second modification example of the thermal resistor 110 according to the first exemplary embodiment. FIG. 7 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. In FIG. 7, the flow direction of the coolant flowing through the coolant path 2 d is indicated by an arrow. The thermal resistor 110 illustrated in FIG. 7 has a curved surface such that the thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d (as indicated by the arrow in FIG. 7). Thus, when the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d, an increase in the flow velocity of the coolant in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d is suppressed. Thus, the thermal boundary layer serving as the thermal resistance is more likely to be formed in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. For this reason, the thermal resistor 110 can further reduce the deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e. As a result, it is possible to further improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Further, the inlet path 2 b may be connected to the coolant path 2 d to be inclined with respect to the flow direction of the coolant flowing through the coolant path 2 d. FIG. 8 is a schematic cross sectional view showing a modification example of the connection between the inlet path 2 b and the coolant path 2 d according to the first exemplary embodiment. FIG. 8 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. In FIG. 8, the flow direction of the coolant flowing through the coolant path 2 d is indicated by an arrow. The inlet path 2 b is extended from the backside of the mounting surface 6 e of the mounting table 2 such that an extension direction of the inlet path 2 b is inclined at an angle θ greater than 90° with respect to the flow direction of the coolant flowing through the coolant path 2 d (as indicated by an arrow in FIG. 8), and then, connected to the coolant path 2 d. Thus, when the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d, the increase in the flow velocity of the coolant in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d is suppressed. Thus, the thermal boundary layer serving as the thermal resistance is more likely to be formed in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. For this reason, the thermal resistor 110 can further reduce the deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e. Thus, it is possible to further improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Further, desirably, the angle θ is equal to or larger than 135° and equal to or smaller than 180°. Thus, it is possible to further reduce the difference in the flow velocity of the coolant between in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d and in the other region. As a result, it is possible to further improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

As described above, the plasma processing apparatus 100 according to the first exemplary embodiment includes the mounting table 2, the coolant path 2 d, the inlet path 2 b, and the thermal resistor 110. The mounting table 2 has the mounting surface 6 e on which the wafer W serving as the plasma processing target is mounted. The coolant path 2 d is formed within the mounting table 2 along the mounting surface 6 e of the mounting table 2. The inlet path 2 b is connected to the coolant path 2 d from the backside of the mounting surface 6 e of the mounting table 2 and introduces the coolant into the coolant path 2 d. The thermal resistor 110 is provided in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. Thus, the plasma processing apparatus 100 can improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Second Exemplary Embodiment

Hereafter, a second exemplary embodiment will be described. The plasma processing apparatus 100 according to the second exemplary embodiment has basically the same configuration as the plasma processing apparatus 100 according to the first exemplary embodiment illustrated in FIG. 1 except a configuration of the mounting table 2. Therefore, components similar or corresponding to those of the above-described exemplary embodiment will be assigned similar reference numerals, and detailed descriptions thereof will be omitted.

Configuration of Mounting Table

A configuration of main components of the mounting table 2 will be described with reference to FIG. 9. FIG. 9 is a schematic cross sectional view illustrating a configuration of main components of the mounting table 2 according to the second exemplary embodiment.

The mounting table 2 includes the base 2 a and the electrostatic chuck 6. The upper surface of the electrostatic chuck 6 serves as the mounting surface 6 e on which the wafer W is mounted. Within the base 2 a, the coolant path 2 d is provided along the mounting surface 6 e. The inlet path 2 b and the outlet path 2 c are connected to the coolant path 2 d from the backside of the mounting surface 6 e of the mounting table 2. The coolant path 2 d is provided with a thermal resistor 210 in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d.

FIG. 10 is a schematic cross sectional view illustrating an example of the thermal resistor 210 according to the second exemplary embodiment. FIG. 10 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. The thermal resistor 210 is made of a material having a lower thermal conductivity than the base 2 a of the mounting table 2. For example, the thermal resistor 210 is made of ceramic, quartz, resin, or the like. The thermal resistor 210 is provided as a member separate from the base 2 a of the mounting table 2 in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. That is, when viewed from the direction orthogonal to the mounting surface 6 e, the thermal resistor 210 is provided at a position overlapping with the connection portion 2 g between the inlet path 2 b and the coolant path 2 d and functions as an insulator between the coolant and a portion, located above the connection portion 2 g, of the base 2 a of the mounting table 2. In the present exemplary embodiment, the thermal resistor 210 has a shape in which a thickness of the thermal resistor 210 is uniform in the flow direction of the coolant flowing through the coolant path 2 d (as indicated by the arrow in FIG. 10).

Further, the thermal resistor 210 may have an inclined shape in which a thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d. FIG. 11 is a schematic cross sectional view showing a first modification example of the thermal resistor 210 according to the second exemplary embodiment. FIG. 11 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. In FIG. 11, the flow direction of the coolant flowing through the coolant path 2 d is indicated by an arrow. The thermal resistor 210 illustrated in FIG. 11 has an inclined surface, so that a thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d (as indicated by the arrow in FIG. 11). Thus, even if the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d, the increase in the flow velocity of the coolant in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d is suppressed. Thus, the thermal boundary layer serving as the thermal resistance is more likely to be formed in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. For this reason, the thermal resistor 210 can further reduce a deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e. As a result, it is possible to further improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Moreover, the thermal resistor 210 may have a curved shape in which a thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d. FIG. 12 is a schematic cross sectional view showing a second modification example of the thermal resistor 210 according to the second exemplary embodiment. FIG. 12 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. In FIG. 12, the flow direction of the coolant flowing through the coolant path 2 d is indicated by an arrow. The thermal resistor 210 illustrated in FIG. 12 has a curved surface, so that the thickness thereof is decreased toward the flow direction of the coolant flowing through the coolant path 2 d (as indicated by the arrow in FIG. 12). Thus, even if the flow direction of the coolant is changed between the inlet path 2 b and the coolant path 2 d, disorder of the flow of the coolant around the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d is suppressed. Thus, the thermal boundary layer serving as the thermal resistance is more likely to be formed in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. For this reason, the thermal resistor 210 can further reduce the deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e. As a result, it is possible to further improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

Further, the thermal resistor 210 may be buried in a region, corresponding to the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. FIG. 13 is a schematic cross sectional view showing a third modification example of the thermal resistor 210 according to the second exemplary embodiment. FIG. 13 corresponds to a cross sectional view taken along the line A-A of the base 2 a of the mounting table 2 illustrated in FIG. 3. In FIG. 13, the flow direction of the coolant flowing through the coolant path 2 d is indicated by an arrow. The thermal resistor 210 illustrated in FIG. 13 is buried in the region, corresponding to the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. The thermal resistor 210 may be buried in the region, corresponding to the connection portion 2 g, of the inner wall of the coolant path 2 d while at least a part of the thermal resistor 210 is exposed to a side of the mounting surface 6 e of the mounting table 2, or may be buried in the region, corresponding to the connection portion 2 g, of the inner wall of the coolant path 2 d while the thermal resistor 210 is not exposed to the side of the mounting surface 6 e of the mounting table 2. Further, the thermal resistor 210 may be buried in the region, corresponding to the connection portion 2 g, of the inner wall of the coolant path 2 d while at least a part of the thermal resistor 210 is exposed to the inner wall of the coolant path 2 d, or may be buried in the region, corresponding to the connection portion 2 g, of the inner wall of the coolant path 2 d while the thermal resistor 210 is not exposed to the inner wall of the coolant path 2 d. In the example illustrated in FIG. 13, an upper end portion of the thermal resistor 210 is exposed to the side of the mounting surface 6 e at the upper surface of the base 2 a of the mounting table 2, so that it reaches the electrostatic chuck 6. Further, a lower end portion of the thermal resistor 210 is exposed to the inner wall of the coolant path 2 d.

Like the thermal resistor 110 according to the first exemplary embodiment, the thermal resistor 210 can make the thermal resistance between the region, facing the connection portion 2 g, of the inner wall of the coolant path 2 d and the mounting surface 6 e close to the thermal resistance between the other region in the coolant path 2 d and the mounting surface 6 e. That is, the thermal resistor 210 can reduce the deviation in the thermal resistance between the coolant flowing through the coolant path 2 d and the mounting surface 6 e.

As described above, in the plasma processing apparatus 100 according to the second exemplary embodiment, the thermal resistor 210 is made of a material having a lower thermal conductivity than the base 2 a of the mounting table 2. Further, the thermal resistor 210 is provided as a member separate from the base 2 a of the mounting table 2 in the region, facing the connection portion 2 g between the inlet path 2 b and the coolant path 2 d, of the inner wall of the coolant path 2 d. Thus, the plasma processing apparatus 100 can improve the temperature uniformity in the mounting surface 6 e of the mounting table 2.

There have been described various exemplary embodiments. However, the present disclosure is not limited to the above-described exemplary embodiments and can be modified and changed in various ways. For example, the above-described plasma processing apparatus 100 is a capacitively coupled plasma processing apparatus, but may be applied to any plasma processing apparatus. For example, the plasma processing apparatus 100 may be any type of plasma processing apparatus such as an inductively coupled plasma processing apparatus or a plasma processing apparatus that excites a gas with a surface wave such as a microwave.

Further, in the above-described exemplary embodiments, there has been described the example where the first RF power supply 10 a and the second RF power supply 10 b are connected to the base 2 a, but the configuration of the plasma source is not limited thereto. For example, the first RF power supply 10 a for plasma generation may be connected to the shower head 16 serving as the upper electrode. Further, the second RF power supply 10 b for ion attraction (for bias) may not be connected to the base 2 a.

Furthermore, the above-described plasma processing apparatus 100 is a plasma processing apparatus configured to perform the etching as the plasma processing, but may be applied to a plasma processing apparatus configured to perform any plasma processing. For example, the plasma processing apparatus 100 may be a single-substrate deposition apparatus configured to perform chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), or the like or may be a plasma processing apparatus configured to perform plasma annealing, plasma implantation, or the like.

From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting. The scope of the inventive concept is defined by the following claims and their equivalents rather than by the detailed description of the exemplary embodiments. It shall be understood that all modifications and embodiments conceived from the meaning and scope of the claims and their equivalents are included in the scope of the inventive concept. 

We claim:
 1. A plasma processing apparatus, comprising: a mounting table having thereon a mounting surface on which a work-piece serving as a plasma processing target is mounted; a coolant path formed within the mounting table along the mounting surface of the mounting table; an inlet path connected to the coolant path from a backside of the mounting surface of the mounting table and configured to introduce a coolant into the coolant path; and a thermal resistor provided in a region, facing a connection portion between the inlet path and the coolant path, of an inner wall of the coolant path.
 2. The plasma processing apparatus of claim 1, wherein the thermal resistor is made of the same material as a base of the mounting table and provided as a single body with the base of the mounting table to be protruded toward the connection portion from the region, facing the connection portion between the inlet path and the coolant path, of the inner wall of the coolant path.
 3. The plasma processing apparatus of claim 1, wherein the thermal resistor is made of a material having a thermal conductivity lower than a base of the mounting table and provided as a member separate from the base of the mounting table in the region, facing the connection portion between the inlet path and the coolant path, of the inner wall of the coolant path.
 4. The plasma processing apparatus of claim 3, wherein the thermal resistor is buried in the region, facing the connection portion between the inlet path and the coolant path, of the inner wall of the coolant path.
 5. The plasma processing apparatus of claim 1, wherein the thermal resistor has an inclined surface such that a thickness thereof is decreased toward a flow direction of the coolant flowing through the coolant path.
 6. The plasma processing apparatus of claim 1, wherein the thermal resistor has a curved surface such that a thickness thereof is decreased toward a flow direction of the coolant flowing through the coolant path.
 7. The plasma processing apparatus of claim 1, wherein the inlet path is extended from a backside of the mounting surface of the mounting table such that an extension direction of the inlet path is inclined at an angle of greater than 90° with respect to a flow direction of the coolant flowing through the coolant path, and then, connected to the coolant path. 